Johan GadolinDied 15 Aug 1852 at age 92 (born 5 Jun 1760).Finnish chemist who discovered the element yttrium (1794). This was the first of a family of 15 rare earth elements called the lanthanides. He studied in Uppsala, Sweden, and taught chemistry there (1797-1822) and promoted Antoine Lavoisier's discoveries about combustion and his system of chemical nomenclature. In analysing a new black mineral from Ytterby, Sweden, he isolating from it the rare earth mineral, yttria. This was an important step towards identifying the remaining undiscovered elements. Over the next century yttria was found to contain the oxides of nine new rare earth elements. After Gadolin's death, one discovered by Jean Charles Galissard de Marignac and Paul Emile Lecoq de Boisbaudran, was named gadolinium.